1. Technical Field
The invention disclosed generally relates to multiple target tracking radar systems which determine the states of individual objects in a clutter environment.
2. Background Art
The present invention is intended for the real time tracking of moving objects in a clutter environment, such as for the purpose of traffic control of aircraft within an air space. The invention is a technique for multiple sensor tracking which distributes the track processing among multiple processing entities, but coordinates the track estimates such that the track states and covariances represent the equivalent of a centralized estimate. In the prior art three basic modes of tracking were available: centralized, single sensor distributed, and combined.
In centralized tracking shown in the prior art of FIG. 1, all sensor data is fed to a central processor. This method is particularly vulnerable to processor failure. However, it produces accurate results because all sensor measurements are used in a close to optimal fashion.
In a sensor level tracking system, the outputs shown in prior art FIG. 2a are available to the user. This method is not as vulnerable to processor failure as a centralized tracking design. This is because in the event of any one sensor or tracking system failure, tracking outputs may be derived from a different sensor with overlapping coverage. However, sensor level tracking does not provide tracking outputs which are as accurate as a centralized design.
In a combined tracking system shown in prior art FIG. 2b, each sensor processor forms a sensor level track. These tracks are then combined at a central processing entity. This method is less vulnerable to processor failure because of the redundancy in the sensor level processors (although the method is still vulnerable to central processor failure). The method also achieves the accuracy of a centralized design. However, the method is computationally expensive since both the sensor level and central processors must be supported, as well as the data communications between the sensor level and central level processors.
What is needed is a method of multiple sensor tracking which is entirely distributed, allowing for better overall tracking system reliability. If any one processing entity or sensor fails, the tracking process should be able to continue. The tracking system should take full advantage of all available sensor inputs for high accuracy. Finally, the communications and processing complexity should be at least as low as for that of sensor level tracking.
The present invention achieves these objectives. That is, the invention fully distributes track processing and produces results which are equivalent in accuracy to results derived from a centralized multiple sensor tracking system. The complexity of the design is low because the computations are entirely distributed.